1. Field of Invention
This invention relates to compounds having antithrombotic activity. More particularly, the invention relates to azacycloalkylalkanoyl peptides and pseudopeptides that inhibit platelet aggregation and thrombus formation in mammals and which are useful in the prevention and treatment of thrombosis associated with disease states such as myocardial infarction, stroke, peripheral arterial disease and disseminated intravascular coagulation.
Haemostasis, the biochemistry of blood coagulation, is an extremely complex phenomena whereby normal whole blood and body tissue spontaneously arrest bleeding from injured blood vessels. Effective haemostasis requires the combined activity of vascular, platelet and plasma factors as well as a controlling mechanism to prevent excessive clotting. Defects, deficiencies, or excesses of any of these components can lead to hemorrhagic or thrombotic consequences.
Platelet adhesion, spreading and aggregation on extracellular matrices are central events in thrombus formation. These events are mediated by a family of adhesive glycoproteins, i.e., fibrinogen, fibronectin, and von Willebrand factor. Fibrinogen is a co-factor for platelet aggregation, while fibronectin supports platelet attachments and spreading reactions, and von Willebrand factor is important in platelet attachment to and spreading on subendothelial matrices. The binding sites for fibrinogen, fibronectin and von Willebrand factor have been located on the platelet membrane protein complex known as glycoprotein IIb/IIIa.
Adhesive glycoproteins, like fibrinogen, do not bind with normal resting platelets. However, when a platelet is activated with an agonist such as thrombin or adenosine diphosphate, the platelet changes its shape, perhaps making the GPIIb/IIIa binding site accessible to fibrinogen. Compounds within the scope of the present invention block the fibrinogen receptor, thus inhibiting platelet aggregation and subsequent thrombus formation and when administered in the form of pharmaceutical compositions comprising such compounds are useful for the prevention and treatment of thrombogenic diseases, such as myocardial infarction, stroke, peripheral arterial disease and disseminated intravascular coagulation.
2. Reported Developments
It has been observed that the presence of Arg-Gly-Asp (RGD) is necessary in fibrinogen, fibronectin, and von Willebrand factor for their interaction with the cell surface receptor (Ruoslahti E., Pierschbacher, Cell 1986, 44, 517-18). Two other amino acid sequences also seem to take part in the platelet attachment function of fibrinogen, namely, the Gly-Pro-Arg sequence, and a dodecapeptide. Small synthetic peptides containing the RGD or dodecapeptide have been shown to bind to the platelet GPIIb/IIIa receptor and competitively inhibit binding of fibrinogen, fibronectin and von Willebrand factor as well as inhibit aggregation of activated platelets (Plow, et al., Proc. Natl. Acad. Sci. USA 1985, 82, 8057-61; Ruggeri, et al., Proc. Natl. Acad. Sci. USA 1986, 5708-12; Ginsberg, et al., J. Biol. Chem. 1985, 260, 3931-36; and Gartner, et al., J. Biol. Chem. 1987, 260, 11, 891-94).
Indolyl compounds containing guanidinoalkanoyl- and guandinoalkenoyl-aspartyl moieties are reported to be platelet-aggregation inhibitors by Tjoeng, et al., U.S. Pat. Nos. 5,037,808 and 4,879,313.
U.S. Pat. No. 4,992,463 (Tjoeng, et al.), issued Feb. 12, 1991, discloses generically that a series of aryl and aralkyl guanidinoalkyl peptide mimetic compounds exhibit platelet aggregation inhibiting activity and discloses specifically a series of mono- and dimethoxy phenyl peptide mimetic compounds and a biphenylalkyl peptide mimetic compound.
U.S. Pat. No. 4,857,508 (Adams, et al.), issued Aug. 15, 1989, discloses generically that a series of guandinoalkyl peptide derivatives containing terminal aralkyl substituents exhibit platelet aggregation inhibiting activity and discloses specifically a series of O-methyl tyrosine, biphenyl, and naphthyl derivatives containing a terminal amide functionality.
Haverstick, D. M., et al., in Blood 66 (4), 946-952 (1985), disclose that a number of synthetic peptides are capable of inhibiting thrombin-induced platelet aggregation.
Plow, E. F., et al., in Proc. Natl. Acad. Sci. USA 79, 3711-3715 (1982), disclose that the tetrapeptide which inhibits fibrinogen binding to human platelets.
French Application No. 86/17507, filed Dec. 15, 1986, discloses that tetra-, penta- and hexapeptide derivatives containing the -arg-gly-asp-sequence are useful as antithrombotics.
U.S. Pat. No. 4,683,291 (Zimmerman, et al.), issued Jul. 28, 1987, discloses that a series of peptides, comprised of from six to forty amino acids, which contain the sequence -arg-gly-asp- are platelet binding inhibitors.
European Application Publication No. 0 319 506, published Jun. 7, 1989, discloses that a series of tetra-, penta-, and hexapeptide derivatives containing the -arg-gly-asp-sequence are platelet aggregation inhibitors.
Cyclic peptide analogues containing the moiety Gly-Asp are reported to be fibrinogen receptor antagonists in U.S. Pat. No. 5,023,233.
Peptides and pseudopeptides containing amino-, guanidino-, imidizaloyl, and/or amidinoalkanoyl, and alkenoyl moieties are reported to be antithrombotic agents in pending U.S. applications Ser. Nos. 07/677,006, 07/534,385, and 07/460,777 filed on Mar. 28, 1991, Jun. 7, 1990, and Jan. 4, 1990, respectively, as well as in U.S. Pat. No. 4,952,562, and in International Application No. PCT/US90/05448, filed Sep. 25, 1990, all assigned to the same assignee as the present invention.
Peptides and pseudopeptides containing amino- and guanidino-alkyl- and alkenyl-benzoyl, phenylalkanoyl, and phenylalkenoyl moieties are reported to be antithrombotic agents in pending U.S. application Ser. No. 07/475,043, filed Feb. 5, 1990, and in International Application No. PCT/US91/02471, filed Apr. 11, 1991, published as International Publication No. WO 92/13117 Oct. 29, 1992, assigned to the same assignee as the present invention.
Alkanoyl and substituted alkanoyl azacycloalkylformyl aspartic acid derivatives are reported to be platelet aggregation inhibitors in U.S. Pat. No. 5,053,392, filed Dec. 1, 1989, and assigned to the same assignee and having the same inventorship as the present invention.
N-subsituted azacycloalkylcarbonyl cyclic aminoacylaspartic acid derivatives are reported to be antithrombotics in U.S. Pat. No. 5,064,814, filed Apr. 5, 1990 by the same inventors and assigned to the same assignee as the present invention. Azacycloalkylformylglycyl aspartic acid derivatives are reported to be antithrombotics in U.S. Pat. No. 5,051,405, filed Oct. 10, 1989, and assigned to the same assignee as the present invention.
European Patent Application 0479,481, published Apr. 8, 1992, discloses azacycloalkyalkanoyl glycyl aspartyl amino acids as fibrinogen receptor antagonists.
European Patent Application 0478,362, published Apr. 1, 1992, discloses azacycloalkyalkanoyl peptidyl b-alanines as fibrinogen receptor antagonists.
The present invention relates to azacycloalkylalkanoyl peptides and pseudopeptides which inhibit platelet aggregation and thrombus fornation.
Compounds of the present invention are described by Formula I 
wherein:
A is xe2x80x94H, amidino, or substituted amidino;
B is alkyl, cycloalkyl, cycloalkylalkyl, alkylcycloalkyl, alkylcycloalkylalkyl, aryl, aralkyl, alkylaryl, or alkylaralkyl;
Z is 
where
E is xe2x80x94H or, in combination with F, forms a 4-, 5-, 6-, or 7-membered azacycloalkane ring,
F is the a-carbon side chain of a naturally occuring a-amino acid, xe2x80x94H, alkyl, cycloalkyl, cycloalkylalkyl, alkylcycloalkyl, alkylcycloalkylalkyl, aryl, substituted aryl, aralkyl, substitued aralkyl, heterocyclyl, substituted heterocyclyl, heterocyclylalkyl, substituted heterocyclylalkyl, or, in combination with E, forms a 4-, 5-, 6-, or 7-membered azacycloalkane ring.
G is alkyl, cycloalkyl, cycloalkylalkyl, alkylcycloalkyl, alkylcycloalkylalkyl, aryl, substituted aryl, aralkyl, substituted aralkyl, heterocyclyl, substituted heterocyclyl, heterocyclylalkyl, substituted heterocyclylalkyl, OR1, or NR1R2, where R1 and R2 are independently xe2x80x94H, alkyl, cycloalkyl, cycloalkylalkyl, alkylcycloalkyl, alkylcycloalkylalkyl, aryl, aralkyl, alkylaryl, or alkylaralkyl, and
r is 0 or 1;
R is Hxe2x80x94, alkyl, aryl, or aralkyl;
m is 1 to 5;
n is 0 to 6; and
p is 1 to 4;
or a pharmaceutically acceptable salt thereof.
Additionally, the present invention relates to pharmaceutical compositions comprising such compounds, and to methods of prevention or treatment of thrombosis in a mammal in need of such therapy comprising the administration of such compounds and pharmaceutical compositions.
The present invention is characterized by the marked and prolonged antithrombotic activity of the compounds of Formula I, above, observed after oral administration thereof.
As used above, and throughout the description of this invention, the following terms, unless otherwise indicated, shall be understood to have the following meanings:
xe2x80x9cAmidinoxe2x80x9d means an 
group.
xe2x80x9cSubstituted amidinoxe2x80x9d means an amidino group N-substituted on one or both nitrogens by one or more alkyl, cycloalkyl, cycloalkylalkyl, alkycycloalkyl, alkylcycloalkylalkyl, aryl or aralkyl groups.
xe2x80x9cAlkylxe2x80x9d means a saturated aliphatic hydrocarbon group which may be straight or branched and having about 1 to about 20 carbon atoms in the chain. Branched means that a lower alkyl group such as methyl, ethyl or propyl is attached to a linear alkyl chain. Preferred straight or branched alkyl groups are the xe2x80x9clower alkylxe2x80x9d groups which are those alkyl groups having from 1 to about 10 carbon atoms. Most preferred lower alkyl groups have from 1 to about 6 carbon atoms.
xe2x80x9cCycloalkylxe2x80x9d means a saturated carbocyclic group having one or more rings and having about 3 to about 10 carbon atoms. Preferred cycloalkyl groups include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, and decahydronaphthyl.
xe2x80x9cCycloalkylalkyl means an alkyl group substituted with a cycloalkyl group. Preferred cycloalkylalkyl groups include cyclopentylmethyl, cyclohexylmethyl, cyclohexylethyl,decahydronaphth-1-ylmethyl and decahydronaphth-2-ylmethyl.
xe2x80x9cAlkylcycloalkylxe2x80x9d means an cycloalkyl group substituted with an alkyl group. Exemplary alkylcycloalkyl groups include 1-, 2-, 3-, or 4-methyl or ethyl cyclohexyl.
xe2x80x9cAlkylcycloalkylalkylxe2x80x9d means an alkyl group substituted by an alkylcycloalkyl group. Exemplary alkylcycloalkyl groups include 1-, 2-, 3-, or 4-methyl or ethyl cyclohexylmethyl or 1-, 2-, 3-, or 4-methyl or ethyl cyclohexylethyl.
xe2x80x9cAzacycloalkanexe2x80x9d means a saturated aliphatic ring containing a nitrogen atom. Preferred azacycloalkanes include pyrollidine and piperidine.
xe2x80x9cNaturally occuring a-amino acidxe2x80x9d means glycine, alanine, valine, leucine, isoleucine, serine, threonine, phenylalanine, tyrosine, tryptophan, cysteine, methionine, proline, hydroxyproline, aspartic acid, asparagine, glutamine, glutamic acid, histidine, arginine, ornithine, and lysine.
xe2x80x9ca-carbon side chain of a naturally occuring a-amino acidxe2x80x9d means the moiety which substitutes the a-carbon of a naturally occuring a-amino acid. Exemplary a-carbon side chains of naturally occuring a-amino acids include isopropyl, methyl, and carboxymethyl for valine, alanine, and aspartic acid, respectively.
xe2x80x9cArylxe2x80x9d means a phenyl or naphthyl group.
xe2x80x9cSubstituted arylxe2x80x9d means a phenyl or naphthyl group substituted by one or more aryl group substitutents which may be the same or different, where xe2x80x9caryl group substituentxe2x80x9d includes alkyl, alkenyl, alkynyl, aryl, aralkyl, hydroxy, alkoxy, aryloxy, aralkoxy, hydroxyalkyl, acyl, formyl, carboxy, alkenoyl, aroyl, halo, nitro, trihalomethyl, cyano, alkoxycarbonyl, aryloxycarbonyl, aralkoxycarbonyl, acylamino, aroylamino, carbamoyl, alkylcarbamoyl, dialkylcarbamoyl, arylcarbamoyl, aralkylcarbamoyl, alkylsulfonyl, alkylsulfinyl, arylsulfonyl, arylsulfinyl, aralkylsulfonyl, aralkylsulfinyl, or xe2x80x94NRaRb where Ra and Rb are independently hydrogen, alkyl, aryl, or aralkyl.
xe2x80x9cAralkylxe2x80x9d means an alkyl group substituted by arraryl radical. Preferred aralkyl groups include benzyl, naphth-1-ylmethyl naphth-2-ylmethyl, and phenethyl.
xe2x80x9cSubstituted aralkylxe2x80x9d means an aralkyl group substituted on the aryl portion by one or more aryl group substituents.
xe2x80x9cHeterocyclylxe2x80x9d means about a 4- to about a 15-membered monocyclic or multicyclic ring system in which one or more of the atoms in the ring is an element other than carbon, for example nitrogen, oxygen, or sulfur. Preferred heterocyclyl groups include pyridyl, pyrimidyl, and pyrrolidyl.
xe2x80x9cSubstituted heterocyclylxe2x80x9d means a heterocyclyl group substitued by one or more aryl group substituents.
xe2x80x9cHeterocyclylalkylxe2x80x9d and xe2x80x9csubstituted heterocyclylalkylxe2x80x9d means an alkyl group which is substituted by a heterocyclyl and substituted heterocyclyl group, respectively.
A preferred class of compounds of the present invention is described by Formula I wherein F is xe2x80x94H, alkyl, hydroxymethyl, 1-hydroxyethyl, mercaptomethyl, 2-methylthioethyl, carboxymethyl, 2-carboxyethyl, 4-aminobutyl, 3-guanidinopropyl, cycloalkyl, cycloalkylalkyl, alkylcycloalkyl, alkylcycloalkylalkyl, aryl, substituted aryl, aralkyl, substituted aralkyl, heterocyclyl, substituted heterocyclyl, heterocyclylalkyl, substituted heterocyclylalkyl, or, in combination with E, forms a 4-, 5-, 6-, or 7-membered azacycloalkane ring, provided that heterocyclylalkyl is other than indol-3-ylmethyl.
A more preferred class of compounds of the present invention is described by the preferred class of compounds wherein F is xe2x80x94H, alkyl, hydroxymethyl, 1-hydroxyethyl, mercaptomethyl, 2-methylthioethyl, carboxymethyl, 2-carboxyethyl, 4-aminobutyl, 3-guanidinopropyl, cycloalkyl, cycloalkylalkyl, alkylcycloalkyl, alkylcycloalkylalkyl, aryl, substituted aryl, aralkyl, substituted aralkyl, or, in combination with E, forms a 4-, 5-, 6-, or 7-membered azacycloalkane ring.
A still more preferred class of compounds of the present invention is described by the more preferred class of compounds wherein F is xe2x80x94H, alkyl, hydroxymethyl, 1-hydroxyethyl, mercaptomethyl, 2-methylthioethyl, carboxymethyl, 2-carboxyethyl, 4-aminobutyl, 3-guanidinopropyl, cycloalkyl, cycloalkylalkyl, alkylcycloalkyl, alkylcycloalkylalkyl, or, in combination with E, forms a 4-, 5-, 6-, or 7-membered azacycloalkane ring.
A most preferred class of compounds of the present invention is described by the still more preferred class of compounds wherein B is alkyl, cycloalkyl, cycloalkylalkyl, alkylcycloalkyl, or alkylcycloalkylalkyl
A special embodiment of the present invention is described by Formula II 
wherein:
A is xe2x80x94H or amidino,
B is alkyl, cycloalkyl, cycloalkylalkyl, alkylcycloalkyl, alkylcycloalkylalkyl, aryl, aralkyl, alkylaryl, or alkylaralkyl,
J is xe2x80x94H, alkyl, cycloalkyl, cycloalkylalkyl, alkylcycloalkyl, alkylcycloalkylalkyl, aryl, substituted aryl, aralkyl, substitued aralkyl,
L is OR1, or NR1R2, where R1 and R2 are independently xe2x80x94H, alkyl, cycloalkyl, cycloalkylalkyl, alkylcycloalkyl, alkylcycloalkylalkyl, aryl, aralkyl, alkylaryl, or alkylaralkyl,
m is 1 to 5,
n is 2 to 6, and
p is 1 or 2;
or a pharmaceutically acceptable salt thereof.
A more preferred special embodiment of the present invention is described by the compounds of the special embodiment wherein
A is xe2x80x94H,
B is alkyl, cycloalkyl, cycloalkylalkyl, alkylcycloalkyl, alkylcycloalkylalkyl,
J is xe2x80x94H, alkyl, cycloalkyl, cycloalkylalkyl, alkylcycloalkyl, or alkylcycloalkylalkyl,
m is 3, and
n is 3 or 4.
A most preferred special embodiment of the special invention is described by the compounds of the more preferred special embodiment wherein
A is xe2x80x94H,
B is alkyl,
J is alkyl, cycloalkyl, or cycloalkylalkyl,
R1 and R2 are independently xe2x80x94H, alkyl, cycloalkyl, cycloalkylalkyl, alkylcycloalkyl, alkylcycloalkylalkyl,
m is 3,
n is 3 or 4, and
p is 1.
Representative compounds of the present invention include:
N-[N-[N-(4-(piperidin-4-yl)butanoyl)-N-ethylglycyl]aspartyl]valine,
N-[N-[N-(4-(piperidin-4-yl)butanoyl)-N-ethylglycyl]aspartyl]-D-valine,
N-[N-[N-(3-(piperidin-4-yl)propanoyl)-N-ethylglycyl]aspartyl]valine,
N-[N-[N-(5-(piperidin-4-yl)pentanoyl)-N-ethylglycyl]aspartyl]valine,
N-[N-[N-(4-(piperidin-4-yl)butanoyl)-N-ethylglycyl]aspartyl]-L-a-cyclohexyl glycine,
N-[N-[N-(4-(piperidin-4-yl)butanoyl)-N-ethylglycyl]aspartyl]-b-cyclohexylalanine,
N-[N-[N-(4-(piperidin-4-yl)butanoyl)-N-ethylglycyl]aspartyl]norleucine,
N-[N-[N-(4-(piperidin-4-yl)butanoyl)-N-ethylglycyl]aspartyl]-L-a-(2,2-dimethyl)prop-3-yl glycine,
N-[N-[N-(4-(piperidin-4-yl)butanoyl)-N-ethylglycyl]aspartyl]-L-b-decahydronaphth-1-yl alanine,
N-[N-[N-(4-(piperidin-4-yl)butanoyl)-N-ethylglycyl]aspartyl]-L-a-(2-cyclohexylethyl)glycine,
N-[N-[N-(4-(piperidin-4-yl)butanoyl)-N-ethylglycyl]aspartyl]phenylalanine,
N-[N-[N-(4-(piperidin-4-yl)butanoyl)-N-ethylglycyl]aspartyl]-L-b-naphth-1-yl alanine,
N-[N[N-(4-(piperidin-4-yl)butanoyl)-N-ethylglycyl]aspartyl]-L-b-naphth-2-yl alanine,
N-[N-[N-(4-(piperidin-4-yl)butanoyl)-N-ethylglycyl]aspartyl]-L-b-cyclohexyl alanine amide,
N-[N-[N-(4-(piperidin-4-yl)butanoyl)-N-ethylglycyl]aspartyl]-L-b-cyclohexyl alanine, ethyl ester,
2-cyclohexyl-N-[N-[N-(4-(piperidin-4-yl)butanoyl)-N-ethylglycyl]aspartyl]-ethylamine,
N-[N-[N-(4-(piperidin-4-yl)butanoyl)-N-ethylglycyl]aspartyl]-L-b-cis-decahydronaphth-2-ylalanine,
3-Adamant-1-ylpropyl-N-[N-(4-(piperidin-4-yl)butanoyl)-N-ethylglycyl]aspartate,
N-[N-[N-(4-(piperidin-4-yl)butanoyl)-N-ethylglycyl]aspartyl]-a-aminocyclohexanecarboxylic acid,
N-[N-[N-(4-(piperidin-4-yl)butanoyl)-N-ethylglycyl]aspartyl]-b-cyclohexyl-D-alanine,
N-[N-[N-(4-(piperidin-4-yl)butanoyl)-N-ethylglycyl]aspartyl]-b-decahydronaphth-1-ylalanine,
N-[N-[N-(4-(piperidin-4-yl)butanoyl)-N-ethylglycyl]aspartyl]-b-cyclohexylalanine ethyl amide,
N-[N-[N-(4-(piperidin-4-yl)butanoyl)-N-ethylglycyl]aspartyl]-b-cyclooctylalanine,
N-[N-[N-(4-(piperidin-4-yl)butanoyl)-N-ethylglycyl]aspartyl]-a-cyclohexylmethylethanolamine,
N-[N-[N-(4-(piperidin-4-yl)butanoyl)-N-ethylglycyl]aspartyl]-b-cyclohexylmethylalanine amide,
N-[N-[N-(4-(piperidin-4-yl)butanoyl)-N-ethylglycyl]aspartyl]-b-adamant-1-ylalanine,
N-[N-[N-(4-(piperidin-4-yl)butanoyl)-N-ethylglycyl]aspartyl]-b-(1,2,3,4)-tetrahydronaphth-5-ylalanine,
N-[N-[N-(4-(piperidin-4-yl)butanoyl)-N-ethylglycyl]aspartyl]-b-(4-cyclohexyl)cyclohexylalanine,
N-[N-[N-(4-(piperidin-4-yl)butanoyl)-N-ethylglycyl]aspartyl]-b-cycloheptylalanine,
N-[N-[N-(4-(piperidin-4-yl)butanoyl)-N-ethylglycyl]aspartyl]-b-cyclooctylalanine amide,
N-[N-[N-(4-(piperidin-4-yl)butanoyl)-N-ethylglycyl]aspartyl]-a-cyclohexylpropylglycine,
N-[N-[N-(4-(piperidin-4-yl)butanoyl)-N-ethylglycyl]aspartyl]-b-cyclooctylmethylalanine,
N-[N-[N-(4-(piperidin-4-yl)butanoyl)-N-ethylglycyl]aspartyl]-b-cyclopentylalanine, and
N-[N-[N-(4-(piperidin-4-yl)butanoyl)-N-ethylglycyl]aspartyl]-b-cyclohexylmethylalanine ethyl ester, and
pharmaceutically acceptable salts thereof.
Compounds of the present invention contain asymmetric centers. These asymmetric centers may independently be in either the R or S configuration. The present invention comprises the individual stereoisomers and mixtures thereof.
The compounds of the present invention may be useful in the form of the free base or acid or in the form of a pharmaceutically acceptable salt thereof. All forms are within the scope of the invention.
Where the compound of the present invention is substituted with a basic moiety, acid addition salts may be formed and are simply a more convenient form for use; and in practice, use of the salt form inherently amounts to use of the free base form. The acids which can be used to prepare the acid addition salts include preferably those which produce, when combined with the free base, pharmaceutically acceptable salts, that is, salts whose anions are non-toxic to the animal organism in pharmaceutical doses of the salts, so that the beneficial antithrombotic properties inherent in the free base are not vitiated by side effects ascribable to the anions. Although pharmaceutically acceptable salts of said basic compounds are preferred, all acid addition salts are useful as sources of the free base form even if the particular salt, per se, is desired only as an intermediate product as, for example, when the salt is formed only for purposes of purification, and identification, or when it is used as intermediate in preparing a pharmaceutically acceptable salt by ion exchange procedures. Pharmaceutically acceptable salts within the scope of the invention are those derived from the following acids: mineral acids such as hydrochloric acid, sulfuric acid, phosphoric acid and sulfamic acid; and organic acids such as acetic acid, citric acid, lactic acid, tartaric acid, malonic acid, methanesufonic acid, ethanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, cyclohexylsulfamic acid, quinic acid, and the like. The corresponding acid addition salts comprise the following: hydrochloride, sulfate, phosphate, sulfamate, acetate, citrate, lactate, tartarate, malonate, methanesulfonate, ethanesulfonate, benzenesulfonate, p-toluenesulfonate, cyclohexylsulfamate and quinate, respectively.
The acid addition salts of the compounds of this invention are prepared either by dissolving the free base in aqueous or aqueous-alcohol solution or other suitable solvents containing the appropriate acid and isolating the salt by evaporating the solution, or by reacting the free base and acid in an organic solvent, in which case the salt separates directly or can be obtained by concentration of the solution.
Where the compound of the invention is substituted with an acidic moiety, base addition salts may be formed and are simply a more convenient form for use; and in practice, use of the salt form inherently amounts to use of the free acid form. The bases which can be used to prepare the base addition salts include preferably those which produce, when combined with the free acid, pharmaceutically acceptable salts, that is, salts whose cations are non-toxic to the animal organism in pharmaceutical doses of the salts, so that the beneficial antithrombotic properties inherent in the free acid are not vitiated by side effects ascribable to the cations. Pharmaceutically acceptable salts within the scope of the invention are those derived from the following bases: sodium hydroxide, potassium hydroxide, calcium hydroxide, aluminum hydroxide, lithium hydroxide, magnesium hydroxide, zinc hydroxide, ammonia, ethylenediamine, N-methyl-glucamine, lysine, arginine, omithine, choline, N,Nxe2x80x2-dibenzylethylenediamine, chloroprocaine, diethanolamine, procaine, N-benzylphenethylamine, diethylamine, piperazine, tris(hydroxymethyl)aminomethane, tetramethylammonium hydroxide, and the like.
Metal salts of compounds of the present invention may be obtained by contacting a hydroxide, carbonate or similar reactive compound of the chosen metal in an aqueous solvent with the free acid form of the compound. The aqueous solvent employed may be water or it may be a mixture of water with an organic solvent, preferably an alcohol such as methanol or ethanol, a ketone such as acetone, an aliphatic ether such as tetrahydrofuran, or an ester such as ethyl acetate. Such reactions are normally conducted at ambient temperature but they may, if desired, be conducted with heating.
Amine salts of compounds of the present invention may be obtained by contacting an amine in an aqueous solvent with the free acid form of the compound. Suitable aqueous solvents include water and mixtures of water with alcohols such as methanol or ethanol, ethers such as tetrahydrofuran, nitrites such as acetonitrile, or ketones such as acetone. Amino acid salts may be similarly prepared.
Compounds of this invention may be prepared in accordance with the reaction sequences described below, or can be prepared by methods known in the art. The starting materials used in the preparation of compounds of this invention are known or are commercially available, or can be prepared by known methods or by specific reaction schemes described herein.
The compounds of the present invention may be readily prepared by standard solid phase or solution phase peptide synthesis procedures using starting materials and/or readily available intermediates from chemical supply companies such as Aldrich or Sigma, (H. Paulsen, G. Merz, V. Weichart, xe2x80x9cSolid-Phase Synthesis of O-Glycopeptide Sequencesxe2x80x9d, Angew. Chem. Int. Ed. Engl. 27 (1988); H. Mergler, R. Tanner, J. Gosteli. and P. Grogg, xe2x80x9cPeptide Synthesis by a Combination of Solid-Phase and Solution Methods I: A New Very Acid-Labile Anchor Group for the Solid-Phase Synthesis of Fully Protected Fragments. Tetrahedron letters 29, 4005 (1988); Merrifield, R. B., xe2x80x9cSolid Phase Peptide Synthesis after 25 Years: The Design and Synthesis of Antagonists of Glucagonxe2x80x9d, Makromol. Chem. Macromol. Symp. 19, 31 (1988)).
A preferred method of preparing compounds of the present invention is by the solution phase method depicted in Scheme I, below. 
wherein A, B, E, F, G, R, m, n, p, and r are as defined hereinabove;
Axe2x80x2, Exe2x80x2, Fxe2x80x2, Gxe2x80x2, and Rxe2x80x2 are A, B, E, F, G, and R, respectively, or are protected analogues thereof, or precursor substituents thereto; and
P1, P2, and P3 are amino acid protecting groups.
The compounds of the present invention are available generally by initially coupling the appropriate amino acid or other appropriate Z group precursor, where Z is as defined hereinabove, which contains a free primary or secondary amine to the free carboxylic acid portion of a protected derivative of aspartic acid.
The functional groups of aspartic acid or any functional groups of the Z group precursor which are not to be coupled are protected where necessary by blocking groups to prevent cross reaction during the coupling procedure, as are the amino acid derivatives and azacycloalkylalkanoic acid derivatives used in subsequent synthetic steps. These blocking groups include N-a-tertiary butyloxycarbonyl (BOC), benzyloxycarbonyl (CBZ), benzyl, methyl, t-butyl, 9-fluorenylmethyloxycarbonyl (FMOC), 2-(trimethylsilyl)ethyl, and 4-methoxy-2,3,6-trimethylbenzenesulfonyl.
A preferred protected derivative of aspartic acid is BOC aspartic acid b-benzyl ester. Coupling is done by methods known in the art. A preferred method for carrying out the coupling is combining the amine and carboxylic acid in an appropriate aprotic organic solvent, for example methylene chloride or dimethylformamide (DMF), in the presence of appropriate coupling agents. A preferred coupling agent is isopropyl chloroformate in the presence of N-methylpiperidine. Another preferred coupling agent is 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) in the presence of 1-hydroxybenzotriazole (HOBT) and triethylamine. Still another preferred coupling agent is bis(2-oxo-3-oxazolidinyl)-phosphonic chloride (BOP-Cl) in the presence of triethylamine.
The resulting protected product is selectively deprotected by known methods to give the N-terminal free amine of the aspartic acid moiety. A preferred method for removing the BOC group is treatment with trifluoroacetic in an aprotic organic solvent, for example, methylene chloride.
The resulting deprotected product is then coupled with the appropriately N-protected N-substituted glycine or b-alanine derivative having a free carboxyl group. The resulting producted is then N-deprotected. The resulting free amine is then coupled with the appropriate protected azacycloalkylalkanoic acid and this product deprotected by known methods to give the final product.
In another preferred method, the compounds of the present invention may be prepared by solid phase methods well known in the art. In the solid method the C-terminal residue is bound at the carboxyl portion to an insoluble resin, for example the residue may be bound as a p-alkoxybenzyl alcohol resin ester. In a manner which is similar to the solution phase method the protected amino acid or other residues are added one at a time until the total sequence has been built up on the resin. The compound is then deprotected and released from the resin by standard methods to give the final compound.
During the preparation of compounds of the present invention, or intermediates thereto, it may also be desirable or necessary to prevent cross-reaction between chemically active substituents other than those present on naturally occuring or other amino acids. The substituents may be protected by standard blocking groups which may subsequently be removed or retained, as required, by known methods to afford the desired products or intermediates (see, for example, Green, xe2x80x9cProtective Groups in Organic Synthesisxe2x80x9d, Wiley, N.Y., 1981). Selective protection or deprotection may also be necessary or desirable to allow conversion or removal of existing substituents, or to allow subsequent reaction to affort the final desired product.
The invention is further explained by the following illustrative examples. In the following examples, unless otherwise indicated, a-amino acids which have the possibility of having chiral a-carbons are in the L configuration.
Unless otherwise indicated, reported mass spectral analysis data are Low Resolution Fast Atom Bombardment performed on a VG 70SE with xe2x80x9ccalculatedxe2x80x9d values being (M+H)+. Nuclear magnetic resonance spectral data is obtained on a Brucker ACF 300, in D2O. Flash chromatography is done on silica gel. High performance liquid chromatography (HPLC) is done on a Dynamax 60 xc3x85, 8xcexc C-18 Reverse Phase column.